spider silk

The reserve’s fields are full of spiders’ webs.

Spider silk is stronger by weight than steel. It is finer than a human hair and, unlike steel, can keep its strength at temperatures below minus 40°C. It is very elastic and the sticky silk a spider uses to catch its prey remains unbroken after being stretched up to four times times its original length. Spider silk is about a sixth of the density of steel and a single strand long enough to circle the Earth would weigh less than 0.5 kilos.

Images: the entrance tunnel to a labyrinth spider‘s complex web.

Spiders use different kinds of silk, each spun from a specific gland, for a variety of functions:

  • spiders wrap their prey in swathing silk;
  • they use sticky silk to build webs for catching prey; it is elastic to prevent the prey from bouncing off the web;
  • draglines, which are used to connect the spider to its web, are safety lines; dragline silk is the strongest kind of silk because it must support the weight of the spider;
  • spiders use parachuting or ballooning silk to catch the wind and lift them into the air. Newly hatched spiderlings disperse to new habitats this way and the webs that can be seen covering our fields when the sun is low is this kind of silk. Spiders have been found 4km up in the atmosphere.
  • They make shelters and nests, and line burrows with silk;
  • females make silken egg-sacs.

Images: a wasp spider‘s web showing a zig zag stabilimentum, the purpose of which is not yet understood; a nursery web spider‘s web providing protection for her hatchlings.

All spiders produce silk, even non-web building spiders.  Silk is also used in courtship and mating rituals; for instance, a female lays a thread of silk to disperse her pheromones and provide a trail for a male to follow in order to find her.

Spider silk is a super-material, one of the strongest materials in the world, biological or manmade. Scientists devote time and resource to studying spider silk in the hope of duplicating its amazing qualities.

The header image is by DKG and all the images used in this post were taken in the reserve.

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